The known art of processing and separating materials in a supply of mixed materials such as commonly found in municipal waste includes apparatus which utilizes a rotary drum within which mixed materials are deposited and separated into light and heavy materials. The drum is inclined at a slight angle to the horizontal and means is provided for loading mixed materials into the interior of the drum while the drum is being rotated. The interior of the drum is provided with longitudinally extending fins or lifters which cause heavy materials to be continuously raised and dropped within the drum so that, because of the inclination of the drum, the materials will eventually work their way toward and out the lower end of the drum.
During this process a stream of air is directed at a relatively high velocity through the drum and in its passage through the drum the air stream entrains light materials and carries them out the upper end of the drum into suitable collecting means such as plenum chambers, cyclones and the like. Thus the light materials are separated within the drum from the heavy materials before the heavy materials have progressed a significant distance down the drum to be removed from the lower end thereof.
It is well known that such separated heavy materials often contain significant amounts of magnetic materials which may have considerable intrinsic values such as warrant their separation from the other materials. Therefore, means has been provided separate from the drum for separating nonmagnetic materials from the magnetic materials in the supply of heavy materials which are extracted from the lower end of the drum. Such additional magnetic separation means usually comprises relatively complicated and expensive apparatus and usually is bulky and space consuming. Some prior devices are known which receive and separate only relatively light materials such as particulates.